The Institute for Healthcare Improvement (IHI) has promoted implementing a RRS to provide safer care for hospitalized patients. Additionally, the Joint Commission made implementing a RRS a 2008 National Patient Safety Goal. Although mandated, the evidence to support the effectiveness of a RRS to reduce cardiac arrests on hospital medical or surgical floors, un-anticipated ICU transfers and all hospital mortality rates remains inconclusive, partly because of weak study designs and partly due to a failure of published studies to report all critical aspects of their intervention. Recently, two published reports have set guidelines for the methodological components that need to be included in published studies of RRS. This study will follow these guidelines to evaluate the effectiveness and the implementation of a RRS on the two campuses of the UMass Memorial Medical Center (UMMMC). The Specific Aims of the proposed research are to: 1) To evaluate the effectiveness of a RRS using a before/after study designed to measure changes in rates of cardiac arrest, un-anticipated ICU admissions from the floors, hospital mortality and code calls to the floor. The before period will consist of a review of the 12 months prior to the implementation of the RSS. The after period will be a review of the 24 months following the implementation of the RSS. 2) To conduct a process evaluation of the RRS intervention that will assess fidelity of RRS implementation, the proportion of the intended patient population that is reached by the RRS, the overall number of RRS calls implemented (dose delivered) and the perceptions of the hospital staff affected by the RRS with respect to acceptability and satisfaction with the RRS and barriers to utilization. An understanding of the effectiveness and the implementation of an RRS will help similar institutions implement or improve an RRS. PUBLIC HEALTH RELEVANCE: Studies have shown that there are often observable clinical antecedents (patient signs and symptoms) to cardiac and respiratory arrests and to ICU admission of patients receiving care on general hospital floors. Other evidence suggests that hospital clinical staff often do not respond effectively to these antecedent clinical findings. In theory, rapid response systems aimed at detection of these antecedents and effective management of the underlying cause/s may reduce the incidence of cardiac and respiratory arrests, of urgent, unplanned ICU admissions, and of in-hospital death among patients hospitalized outside of ICUs. However, evidence on the effectiveness of rapid response systems is limited and the optimal design of the systems is not known. Hospital staff time and energy are limited public health resources that should be allocated in the most cost effective manner. The proposed evaluation of a rapid response system will provide valid measures of the effectiveness of the intervention as well as an understanding of the operation and contribution of the components to the outcomes. The study findings will inform the ongoing national discussion about the benefits and costs of rapid response systems, and may ultimately contribute to a more efficient allocation of the relevant public health resources.